What is the difference between GPON and EPON?

GPON offers higher downstream bandwidth and better QoS. EPON provides symmetric bandwidth at lower cost. GPON supports split ratios up to 1:128 for wider coverage.

Which ONU/ONT is compatible with my OLT?

Our L880G and L801 series ONUs support XPON dual-mode and work with Huawei, ZTE, FiberHome and other major OLT brands. Contact support to confirm compatibility.

What is the difference between SC/APC and SC/UPC connectors?

SC/APC (Angled Physical Contact) and SC/UPC (Ultra Physical Contact) are two common fiber optic connector polish types. The key difference is the end-face angle.SC/UPC: Flat end-face with slight curve, return loss ≥50dB. Used for general-purpose data transmission. Blue color.SC/APC: 8° angled end-face, return loss ≥60dB. Used for RF video transmission (CATV) and PON networks. Green color.They are NOT interchangeable — mixing them can damage the connector end-face.

How do I choose the right fiber optic splitter for my network?

Choosing the right fiber optic splitter depends on several factors:Type: PLC splitters offer better performance for FTTx; FBT splitters suit smaller setupsRatio: Common ratios: 1×2, 1×4, 1×8, 1×16, 1×32, 1×64Package: ABS box (indoor), Mini steel tube (tight spaces), LGX cassette (rack mount)Connector: SC/APC for CATV, SC/UPC for dataFor GPON/EPON FTTH deployments, a 1×8 or 1×16 PLC splitter with SC/APC connectors is recommended.

What is the maximum distance for fiber optic transmission?

Fiber optic transmission distance depends on fiber type and equipment:Single-mode fiber (OS2): Up to 40km+ without amplificationMulti-mode fiber (OM1-OM5): 300m to 550m at 10GbpsGPON: Typically 20km reachEPON: Typically 20kmXGS-PON: Up to 40km1550nm wavelength has lower attenuation (≈0.2dB/km) vs 1310nm (≈0.35dB/km). For standard GPON FTTH, 20km is typical from OLT to ONU.

How do I configure an ONU/ONT for my fiber network?

Configuring an ONU/ONT involves these steps:Connect: Plug fiber cable into PON port, Ethernet to your router/PCPower on: Wait for PON LED to turn solid (optical signal received)Access web: Set PC to same subnet (192.168.1.x), open ONU IP (usually 192.168.1.1)Configure WAN: Set connection type (PPPoE, DHCP, or Static IP) per ISP requirementsRegister: Some ISPs require registration via serial number, LOID password, or MAC address

What is XGS-PON and how is it different from GPON?

XGS-PON (10 Gigabit Symmetric PON) is the next-generation PON technology offering 10Gbps symmetric bandwidth. Key differences from GPON:Speed: GPON = 2.5Gbps down / 1.25Gbps up. XGS-PON = 10Gbps both directionsWavelength: XGS-PON uses 1577nm down / 1270nm up (different from GPON's 1490nm/1310nm)Coexistence: XGS-PON can share the same fiber with GPON via WDMXGS-PON ONUs work with dual-mode OLTs but need an XGS-PON port for 10G speeds. Ideal for 4K/8K streaming, cloud computing, and enterprise use.

How Many Homes Can One OLT Port Serve?

In GPON networks, one OLT port typically serves 32 to 128 homes, depending on the split ratio. A 1:32 splitter is most common for FTTH deployments. With XGS-PON, one port can serve 256+ subscribers. Actual capacity depends on bandwidth per user — if each user needs 100Mbps, a GPON port (2.5Gbps down) handles ~25 users at peak. For our 2-port EPON OLT (L202), each port supports up to 64 ONUs, giving a total of 128 homes per device.

How Is GPON Data Secured on Fiber Optic Networks?

GPON uses AES-128 encryption to secure downstream data. Each ONU receives only its own data — the OLT encrypts traffic with a unique key per ONU. Upstream data is inherently secure because each ONU transmits in its assigned time slot. AES encryption is enabled by default in most OLTs like our EPON/GPON models. For additional security, MAC address filtering and ONU authentication are supported.

Is Fiber Optic Cheaper Than Copper in the Long Run?

Yes. While fiber optic cabling costs 20-30% more upfront, its total cost of ownership (TCO) over 10 years is 40-60% lower than copper. Fiber supports 40Gbps+ bandwidth vs copper's 10Gbps limit, has 25+ year lifespan (copper: 5-10 years), and needs no signal repeaters for up to 40km. For ISPs, the breakeven point is typically 2-3 years. Our single-mode fiber patch cables and splitters provide reliable long-term infrastructure.

25G to 1.6T Ethernet Speed Evolution Roadmap & Module Guide

25G to 1.6T Ethernet Speed Evolution Roadmap: Standards, Optical Modules & AI Impact

01/05/2026 Langzhi Technology

Complete guide to Ethernet speed evolution from 25G to 1.6T. Covers IEEE standards, SFP28/QSFP28/QSFP-DD/OSFP form factors, NRZ/PAM4/Coherent signaling, and deployment guidance for data centers and AI clusters.

Ethernet Speed Evolution Overview

From 2.94Mbps in 1973 to 800G/1.6T today, Ethernet speeds have been accelerating faster than ever, driven primarily by AI/ML workloads. Per the Ethernet Alliance 2026 Roadmap, data centers have evolved from 10G servers to 25G/100G/400G/800G interconnects.

Speed Standards at a Glance

25G: SFP28, 1×25G NRZ, server access. 40G: QSFP+, 4×10G, legacy DC. 50G: SFP56, 2×25G, 5G fronthaul. 100G: QSFP28, 4×25G NRZ, mainstream DC. 200G: QSFP56, 4×50G PAM4, AI back-end. 400G: QSFP-DD/OSFP, 8×50G or 4×100G PAM4, hyperscale. 800G: OSFP/QSFP-DD, 8×100G PAM4, AI clusters. 1.6T: OSFP, 8×200G PAM4/Coherent, next-gen AI.

Signaling Evolution

NRZ (25G/lane and below) → PAM4 (50G/lane and above) → Coherent (100G/lane and above for long-haul).

Selection Guide

Enterprise: 25G servers + 100G spine-leaf. Mid-size DC: 100G QSFP28. Hyperscale: 400G QSFP-DD, migrating to 800G. AI clusters: 400G/800G minimum, 1.6T in 2-3 years.

Langzhi Technology offers SFP28, QSFP28, QSFP-DD optical modules from 25G to 400G.